2-(4-(5-Chloro-3-fluoropyridin-2-yloxy)-phenoxy)-propionic acid derivatives having herbicidal activity

ABSTRACT

There are described novel 2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acids esters and -thio-esters having a herbicidal action and an action reducing the growth of grasses, which compounds correspond to the formula I ##STR1## wherein Q is oxygen or sulfur, 
     R 1  is hydrogen or methyl 
     R 2  is hydrogen or C 1  -C 4  alkyl 
     The salts and enantiomers of these compounds are also part of the invention. 
     These compounds are suitable for selectively controlling weeds in crops of cultivated plants, and for reducing the growth of grasses.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of Ser. No. 07/062,937 filed 06/16/87(abandoned), which is a continuation of Ser. No. 06/858,729 filed05/02/86, (abandoned), which is a continuation-in-part of Ser. No.06/677,775 filed 12/03/84, (abandoned), which is a continuation-in-partof Ser. No. 06/450,815, filed 12/20/82, now U.S. Pat. No. 4,505,743.

The present invention relates to novel2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidderivatives having herbicidal activity, to their production, tocompositions containing these derivatives as active ingredients, andalso to the use thereof as herbicides in general, and in particular forcontrolling weeds in crops of cultivated plants, such as cereals, rice,maize, soyabean and sugar beet.

The 2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidderivatives correspond to the formula I ##STR2## wherein Q is oxygen orsulfur;

R₁ is hydrogen or methyl;

R₂ is hydrogen or C₁ -C₄ alkyl and to the salts and enantiomers of thesecompounds.

Especially effective are the following compounds and their(2R)-enantiomers:

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethoxycarbonylmethyl ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethoxycarbonylmethylthioester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidethoxycarbonylmethyl ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidethoxycarbonylmethylthio ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidn-butoxycarbonylmethyl ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidn-butoxycarbonylmethylthioester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethoxycarbonyl-eth-1-yl ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethoxycarbonyl-eth-1-ylthio ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidethoxycarbonyl-eth-1-yl ester,

2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidethoxycarbonyl-eth-1-ylthio ester,

(2R)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethoxycarbonylmethyl ester,

(2R)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionicacid-methoxycarbonylmethylthio ester,

(2R)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethoxycarbonyl-eth-1-yl ester,

(2R)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidethoxycarbonylmethylthio ester.

The 2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidesters according to the invention are characterised by a good actionagainst mono- and some dicotyledonous weeds; they are above alleffective in the post-emergence process against undesirable weeds andwild grasses occurring in cultivated crops, such as crops of cereals,maize, rice, soyabean and sugar beet. A particularly valuable aspect isthat it is possible with the novel derivatives to combat wild grasseswhich are very difficult to control, for example Avena fatua, Avenasterilis, Alopecurus myosuroides, Lolium perenne, Phalaris sp. Bromustectorum and various species of Setaria and Panicum. The action underfield conditions is achieved even with small applied amounts of lessthan 1 kg per hectare, at which levels the cultivated crops are notharmed, or are harmed to only a negligible extent.

Halopyridyloxy-α-phenoxy-propionic acid derivatives have been describedin numerous publications (cp. for example the GermanOffenlegungsschriften Nos. 2,546,251, 2,649,706, 2,714,622 and2,715,284, and the European Publications Nos. 483 and 1473). In thesepublications, the2-[4-(3-fluoro-5-halopyridin-2-yloxy)-phenoxy]-propionic acidderivatives according to the present invention have in part been takeninto consideration and concomitantly included in the scope. Compounds ofthis type however have not been produced or tested. They aredistinguished from the known halopyridyloxy-α-phenoxy-propionic acids bya better action.

The amounts applied can vary within wide limits, for example between0.05 and 5 kg of active substance per hectare.

The novel compounds of the formula I can be produced by differentmethods which are mostly conventional.

One of these processes comprises reacting 5-chloro-2,3-difluoropyridineof the formula II ##STR3## in an inert solvent or diluent and in thepresence of the equimolar amount of a base, with a racemic orenantiomeric 4-hydroxyphenoxy-α-propionic acid ester of the formula III##STR4## wherein Q, R₁ and R₂ have the meanings defined under theformula I.

A second process comprises reacting a4-(5-chloro-3-fluoropyridin-2-yloxy)-phenol of the formula IV ##STR5##in an inert solvent or diluent and in the presence of the equimolaramount of a base, with a racemic or entantiomeric α-halopropionic acidester of the formula V ##STR6## wherein Hal is halogen, and Q, R₁ and R₂have the meanings defined under the formula I.

A further process comprises reacting a racemic or enantiomeric2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid halideof the formula VI ##STR7## wherein Hal is halogen, in an inert solventor diluent and in the presence of the equimolar amount of a base, withan alcohol or thiol of the formula VII ##STR8## wherein Q, R₁ and R₂have the meanings defined under the formula I.

In addition, the compounds of the formula I can be produced by reactinga racemic or enantiomeric2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid or-thiopropionic acid of the formula IX ##STR9## wherein Hal and Q havethe meanings defined under the formula I, in an inert solvent or diluentand in the presence of the equimolar amount of a base, with a halide ofthe formula X ##STR10## wherein Hal is halogen, R₁ and R₂ have themeaning defined under the formula I.

Finally, a further process comprises converting a racematic orenantiomeric 2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionicacid ester of the formula XI ##STR11## wherein Q, R₁ and R₂ have themeanings defined under the formula I, using known methods, into adiazonium salt, and converting this further into the fluorine compounds.

The (2R)-enantiomers of the compound of formula I are also prepared byreacting in an inert organic solvent in the presence of a base4-(5-chloro-3-fluoropyridin-2-yloxy)-phenol of the formula IV ##STR12##with (S)-lactic acid methylester-sulfonate of the formula XII ##STR13##wherein R₃ is a C₁ -C₆ alkyl group which is straight-chain or branched,and which is unsubstituted or substituted by halogen, cyano, C₁ -C₄alkoxycarbonyl or is a phenyl group which is unsubstituted orsubstituted by C₁ -C₄ alkyl, C₁ -C₄ alkoxy, halogen, nitro, cyano, C₁-C₄ alkoxycarbonyl and R is a C₁ -C₆ alkyl group, and converting theresulting (R)-2[4-(3-fluoro-5-halopyridin-2-yloxy)-phenoxy]-propionicacid ester obtained, by known procedures, to the corresponding(R)-2-[4-(3-fluoro-5-halopyridin-2-yloxy)-phenoxy]-propionic acid halideof the formula VI ##STR14## wherein Hal' is halogen and reacting thishalide in an inert organic solvent in the presence of a base with analcohol or thiol of the formula VII ##STR15## wherein Q, R₁ and R₂ havethe meanings given under formula I.

The starting material of formula II, 5-chloro-2,3-difluoropyridine maybe prepared by fluorinating the corresponding 2,3,5-trichloropyridine inthe presence of cesium fluoride. The products can be distilled off thereaction mixture and have to be purified by fractionate distillation. Itis also possible to obtain 5-chloro-2,3-difluoropyridine starting from2,5-dichloro-3-nitropyridine, which is reduced by means of hydrogen inthe presence of e.g. Raney-nickel catalyst to3-amino-2,5-dichloropyridine. This compound is then converted withsodium nitrite in the presence of hydrofluoric acid to2,5-dichloro-3-fluoropyridine. This latter product can then befluorinated in a good yield by means of potassium-fluoride to2,3-difluoro-5-chloropyridine.

The starting material of formula IV4-(5-chloro-3-fluoropyridin-2-yloxy)-phenol can be obtained bycondensing in an inert organic solvent, in the presence of a base5-chloro-2,3-difluoropyridine and hydroquinone.

The starting material of formula XI can be obtained e.g. by reducing thecorresponding racemic or enantiomeric2-[4-(5-chloro-3-nitropyridin-2-yloxy)-phenoxy]-propionic acid estersknown e.g. from the German Offenlegungsschrift No. DE-A 2 732 846.

The remaining starting material are either known or can easily beprepared by conventional means.

A number of these reactions are advantageously carried out in an organicsolvent or diluent inert to the reactants, for example an alcohol,ester, ether, ketone, dimethylformamide, dimethyl sulfoxide,acetonitrile, 1,1-dioxytetrahydrothiophene or an aromatic compound, suchas toluene and xylene.

The reaction temperatures are between -10° C. and 150° C., in practicehowever between room temperature and the boiling point of the solvent.Depending on the chosen starting material, the solvent and thetemperature, the reaction time is between 1 hour up to about 1 day.

Where a halogen atom is detached in the reaction, the equimolar amountof an acid-binding agent should be used. Suitable as such is essentiallyany inorganic or organic base, for example NaOH, KOH, NaHCO₃, K₂ CO₃ orK-tertbutylate, and amines, such as trimethylamine, triethylamine,pyridine, 4-dimethylaminopyridine, and so forth.

The novel active substances of the formula I are stable compounds whichare soluble in customary organic solvents, such as alcohols, ethers,ketones, dimethylformamide, dimethyl sulfoxide, and the like. Thecompounds show favorable results in chronical toxicity studies tomammals.

The compounds of the formula I are used either in an unmodified form orpreferably together with auxiliaries customarily employed in formulationpractice, and are thus processed in a known manner for example into theform of emulsion concentrates, directly sprayable or dilutablesolutions, diluted emulsions, wettable powders, soluble powders, dustsor granulates, and also encapsulations in for example polymericsubstances. The application processes, such as spraying, atomising,dusting, scattering or pouring, and likewise the type of composition,are selected to suit the objectives to be achieved and the givenconditions.

The formulations, that is to say, the compositions or preparationscontaining the active substance of the formula I and optionally a solidor liquid additive, are produced in a known manner, for example by theintimate mixing and/or grinding of the active substances with extenders,such as with solvents, solid carriers and optionally surface-activecompounds (tensides).

Suitable solvents are: aromatic hydrocarbons, preferably the fractionsC₈ to C₁₂, such as xylene mixtures or substituted naphthalenes, phthalicesters, such as dibutyl- or dioctylphthalate, aliphatic hydrocarbons,such as cyclohexane or paraffins, alcohols and glycols, as well as etherand esters thereof, such as ethanol, ethylene glycol, ethylene glycolmonomethyl or -ethyl ethers, ketones such as cyclohexanone, stronglypolar solvents, such as N-methyl-2-pyrrolidone, dimethyl sulfoxide ordimethylformamide, as well as optionally epoxidised vegetable oils, suchas epoxidised coconut oil or soybean oil; or water.

The solid carriers used, for example for dusts and dispersible powders,are as a rule natural mineral fillers, such as calcite, talcum, kaolin,montmorillonite or attapulgite. In order to improve the physicalproperties, it is possible to add highly dispersed silicic acid orhighly dispersed absorbent polymers. Suitable granulated adsorptivecarriers are porous types, for example pumice, ground brick, sepioliteor bentonite; and suitable nonsorbent carriers are materials such ascalcite or sand. There can also be used a great number of pre-granulatedmaterials of inorganic or organic nature, such as in particular dolomiteor ground plant residues.

Suitable surface-active compounds are, depending on the nature of theactive substance of the formula I to be formulated, nonionic, cationicand/or anionic tensides having good emulsifying, dispersing and wettingproperties. By `tensides` are also meant mixtures of tensides.

Suitable anionic tensides are both so-called water-soluble soaps as wellas water-soluble, synthetic, surface-active compounds.

Soaps which are applicable are for example the alkali metal,alkaline-earth metal or optionally substituted ammonium salts of higherfatty acids (C₁₀ -C₂₀), for example the Na or K salts of oleic orstearic acid, or of natural fatty acid mixtures, which can be obtainedfor example from coconut oil or tallow oil. Also to be mentioned are thefatty acid-methyl-taurine salts.

So-called synthetic tensides are however more frequently used,particularly fatty sulfonates, fatty sulfates, sulfonated benzimidazolederivatives or alkylarysulfonates. The fatty sulfonates or sulfates areas a rule in the form of alkali metal, alkaline-earth metal oroptionally substituted ammonium salts, and contain an alkyl group having8 to 22 C atoms, `alkyl` including also the alkyl moiety of acyl groups,for example the Na or Ca salt of ligninsulfonic acid, of dodecylsulfuricacid ester or of a fatty alcohol sulfate mixture produced from naturalfatty acids. Included among these are also the salts of sulfuric acidesters and sulfonic acids of fatty alcohol ethylene oxide adducts. Thesulfonated benzimidazole derivatives preferably contain 2 sulfonic acidgroups and a fatty acid group having 8-22 C atoms. Alkyarylsulfonatesare for example the Na, Ca or triethanolamine salts ofdodecylbenzenesulfonic acid, of dibutylnaphthalenesulfonic acid or of anaphthalenesulfonic acid-formaldehyde condensation product. Alsosuitable are corresponding phosphates, for example salts of thephosphoric ester of a p-nonylphenol-(4-14)-ethylene oxide adduct.

Suitable nonionic tensides are in particular polyglycol etherderivatives of aliphatic or cycloaliphatic alcohols, saturated orunsaturated fatty acids and alkylphenols, which can contain 3 to 30glycol ether groups and 8 to 20 carbon atoms in the (aliphatic)hydrocarbon radical and 6 to 18 carbon atoms in the alkyl moiety of thealkylphenols.

Further suitable nonionic tensides are the water-soluble polyethyleneoxide adducts, which contain 20 to 250 ethylene glycol ether groups and10 to 100 propylene glycol ether groups, with polypropylene glycol,ethylenediaminopolypropylene glycol and alkylpolypropylene glycol having1 to 10 carbon atoms in the alkyl chain. The compounds mentioned usuallycontain 1 to 5 ethylene glycol units per propylene glycol unit. Examplesof nonionic tensides which may be mentioned are:nonylphenolpolyethoxyethanols, castor oil polyglycol ethers,polypropylene/polyethyleneoxy adducts, tributylphenoxypolyethoxyethanol,polyethylene glycol and octylphenoxypolyethoxyethanol. Suitable also arefatty acid esters of polyoxyethylenesorbitan, such aspolyoxyethylenesorbitan-trioleate.

In the case of the cationic tensides, they are in particular quaternaryammonium salts which contain as N-substituents at least one alkyl grouphaving 8 to 22 carbon atoms and, as further substituents, lower,optionally halogenated alkyl, benzyl or lower hydroxyalkyl groups. Thesalts are preferably in the form of halides, methyl sulfates or ethylsulphates, for example stearyltrimethylammonium chloride orbenzyldi(2-chloroethyl)ethylammonium bromide.

The tensides customarily used in formulation practice are described,inter alia, in the following publications:

"Mc Cutcheon's Detergents and Emulsifiers Annual", MC Publishing Corp.,Ridgewood, N.J., 1979,

Sisely and Wood, "Encylopedia of Surface Active Agents", ChemicalPublishing Co., Inc. New York, 1964.

These preparations contain as a rule 0.1 to 99%, particularly 0.1 to95%, of active substance of the formula I, 1 to 99% of a solid or liquidadditive, and 0 to 25%, especially 0.1 to 25%, of a tenside.

Whereas commercial products are preferably in the form of concentratedcompositions, the compositions employed by the end-user are as a rulediluted.

The compositions can also contain further additives, such asstabilisers, antifoaming agents, viscosity regulators, binders andadhesives, and also fertilisers or other active ingredients forobtaining special effects.

The following Examples describe in detail the production of a2-[4-(3-fluoro-5-chloropyridin-2-yloxy)-phenoxy]-propionic acid ester ofthe formula I according to the invention, and also compositionscontaining such esters as active ingredients. Further esters accordingto the invention which are obtained analogously are listed in the Tablefollowing Example 1. Percentages relate to weight.

EXAMPLE 1 Preparation of2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidethoxycarbonylmethyl ester ##STR16##

A mixture of 10.68 g (0.032 mol) of sodium2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionate and 4.3 g(0.032 mol) bromacetic acid ethyl ester in 30 ml of dimethylformamideare heated for 1 hour at 80° C. The reaction mixture is then poured ontoice-water and extracted three times with ethylacetate. The extracts arewashed with water, then with brine and dried over magnesium sulfate,filtered and concentrated by evaporation. The remaining oil is passedwith petroleum ether/ether 1:1 over a short silicagel column. After thesolvent has been evaporated off, there remains 10.2 g of a clear oiln_(D) ³⁵ 1.5227.

The starting material, the sodium salt of2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionate is obtainedas follows:

(a) 3-amino-2,3-dichloropyridine

To a solution of 129.2 g (0.69 mol) of 2,5-dichloro-3-nitropyridine in1300 ml of dioxane is added 26.0 g of Raney-nickel, that has previouslybeen washed with ethanol. This mixture is then hydrogenated withhydrogen under normal pressure at 20°-35° C. After uptake of 20% of thetheoretical amount of hydrogen, another 30 g of washed Raney-nickelcatalyst are added. After hydrogenating for 22 hours, the catalyst isfiltered off, the solvent is evaporated and the residue is crystallizedfrom hexane/ethyl acetate. Thus, 84.9 g of 3-amino-2,5-dichloropyridine(78% of the theory) are obtained, which melts at 129°-132° C.

(b) 2,5-dichloro-3-fluoropyridine

To 450 ml (22.5 mol) of hydrogen fluoride in a stainless steel reactionvessel are added at a temperature of -5° to -1°, 163 g (1.0 mol) of3-amino-2,5-dichloropyridine. Then there are added while stirring at thesame temperature 82.8 g (1.2 mol) of sodium nitrite into the solution.The reaction mixture is stirred for 1.5 hours at -5° to -1°, then thetemperature is slowly raised to +60° C. After the evolution of gas hasceased, the hydrogen fluoride is distilled off and the residue is takenup in methylene chloride. Ice/water is then added thereto and the coldmixture is neutralized with concentrated ammonium hydroxide solution.The organic phase separated and the water phase is extracted three timeswith methylene chloride. The organic phases are washed with water, driedover magnesium sulfate, filtered through silicagel and evaporated. Thus,141.5 g (85% of the theory) of 2,5-dichloro-3-fluoropyridine areobtained.

(c) 5-chloro-2,3-difluoropyridine

A suspension of 64.6 g (1.1 mol) of potassium fluoride and 11.25 g(0.075 mol) of cesium-fluoride in 240 ml of sulfolane(1,1-dioxo-tetrahydrothiophene) is heated to 140° C. By reducing thepressure 50 ml of sulfolane are distilled off. To the suspension asolution of 61.4 g (0.37 mol) of 2,5-dichloro-3-fluoropyridine in 20 mlof sulfolane is added. The reaction-mixture is then stirred for 35 hoursat a temperature of 140°, cooled and poured into ice/water. The organicmaterial is extracted with ether. The ethereal layer is washed withwater dried over magnesium sulfate, filtered and evaporated to yield48.7 g of a colourless oil (88% of the theory) which boils at 65°-66° at133 mbar.

(d) 2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidmethyl ester

To a stirred mixture of 21.6 g (0.11 mol) of2-(4-hydroxyphenoxy)-propionic acid methyl ester, 15.2 g (0.11 mol) ofpotassium carbonate, 1.45 g (0.0055 mol) of 18-Crown-6 ether and 100 mlof acetonitrile is added dropwise a solution of 14.95 g (0.10 mol) of5-chloro-2,3-difluoropyridine in 30 ml of acetonitrile and the mixtureis heated at a temperature of 50° to 60° C. during 40 hours. The mixtureis then poured into ice/water. The organic material is extracted withethyl acetate, washed with a saturated salt solution, dried overmagnesium sulfate, filtered and evaporated. The oily residue is purifiedby chromatography over a silica gel column with a hexane/ethyl acetate3:1 solvent. After evaporation of the solvent one obtain 20.4 g of theabove ester (63% of the theory) is obtained in crystalline form. Themelting point is 63°-64° C.

(e) 2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidsodium salt

To a solution of 13.0 g (0.04 mol)2-[4-(5-chloro-3-fluoropyridin-2-yloxy)]-propionic acid methyl ester in65 ml of dioxane is added 42 ml of 1N sodium hydroxide. Then it isstirred for 21/2 hours at a temperature of 35° C. The mixture is thenconcentrated to dryness at room temperature in a rotatory evaporator.The remaining salt 13.2 g is used without further purification.

According to this example, the following compounds are prepared:##STR17##

                  TABLE 1                                                         ______________________________________                                        No.       R.sub.1                                                                              Q         R.sub.2 Physical data                              ______________________________________                                        1.01      CH.sub.3                                                                             O         C.sub.2 H.sub.5                                                                       n.sub.D .sup.35 1.5227                     1.02      CH.sub.3                                                                             O         CH.sub.3                                           1.03      CH.sub.3                                                                             S         C.sub.2 H.sub.5                                    1.04      CH.sub.3                                                                             S         CH.sub.3                                           1.05      H      O         C.sub.2 H.sub.5                                    1.06      H      O         CH.sub.3                                           1.07      H      S         C.sub.2 H.sub.5                                    1.08      H      S         CH.sub.3                                                                              n.sub.D .sup.35 1.5607                     1.09      H      O         C.sub.4 H.sub.9 -n                                                                    n.sub.D .sup.35 1.5223                     1.10      H      S         C.sub.4 H.sub.9 -n                                 ______________________________________                                    

EXAMPLE 2 Preparation of the(R)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidchloride ##STR18##

10.8 g (0.035 mol) of (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid aredissolved in 150 ml of toluene. Then 50 ml of toluene are distilled offin an oil-bath that has a temperature of 130°. The reaction mixture isthen cooled down to 90° and 3.8 ml of thionyl chloride are added slowlythereto. The mixture is stirred for 16 hours at 90° and then evaporatedunder reduced pressure. The residue crystallizes and has a melting pointof 47° to 48°.

This chloride is combined with esters of lactic and thiolactic acid toyield optically active esters of4-(5-chloro-3-fluoro-pyridin-2-yloxy)-phenoxy]-propionic acid.

The enantiomers of Table 2 are prepared in this manner.

The (R) (+)-2-[4-(chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionicacid needed as starting material is obtained as follows:

(a) 4-(5-chloro-3-fluoropyridin-2-yloxy)-phenol

A mixture of 27.5 g (0.25 mol) of hydroquinone, 11.2 g (0.2 mol) ofpotassium hydroxide in 600 ml of dimethylsulfoxide is stirred at roomtemperature under a nitrogen atmosphere until everything is dissolved. Asolution of 30 g (0.2 mol) of 5-chloro-2,3-difluoropyridine in 200 ml ofdimethylsulfoxide is added dropwise thereto. The reaction mixture isthen heated to 70° and stirred at that temperature for 4 hours. Then itis poured into ice/water and the mixture is acidified with hydrochloricacid, extracted with ethyl acetate, dried over magnesium sulfate,filtered and evaporated to dryness. The residue is taken up in ahexane/ethyl acetate 2:1 solvent and passed over a silicagel column forpurification. After concentrating the eluate, the residue crystallizesto yield 33 g of white crystals, melting at 97°-98°.

(b) (R) (+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionicacid methyl ester

A solution of 24 g (0.1 mol) of4-(5-chloro-3-fluoropyridin-2-yloxy)-phenol in 80 ml ofdimethylsulfoxide is added dropwise to a stirred solution of 13.8 g (0.1mol) of potassium carbonate in 50 ml of dimethylsulfoxide. Wheneverything is added, the mixture is stirred for 2 hours at roomtemperature and then a solution of 25.8 g (0.1 mol) of (S)(-)-lacticacid-methylester tosylate is added dropwise over 30 minutes. The mixtureis heated to 60° and stirred at that temperature for 20 hours, thenpoured onto ice/water and the organic material is extracted three timeswith ether. The ether-layer is washed with water and saturated saltsolution, dried over magnesium sulfate, filtered and evaporated. Theresidue is passed for purification through a silicagel column with ahexane/ethyl acetate 3:1 solvent. After distillation of the solvent, 26g of a clear oil of the above ester is obtained ([α]_(D) ²⁰=+38.8°±0.5°2% in acetone).

(c) (R) (+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionicacid

To a solution of 13.0 g (0.04 mol) of (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)]-methyl ester in 65 ml ofdioxane are added 42 ml of 1N sodium hydroxide and the mixture isstirred for 21/2 hours at a temperature of 35°. Then it is poured ontoan ice/water mixture and acidified with 22 ml of 2N hydrochloric acid.The organic material is extracted therefrom twice with ethyl acetate.The organic layers are washed with a saturated salt solution and driedover magnesium sulfate, filtered and concentrated. The residue iscristallized from ethyl acetate/hexane and yields 10.2 g (81.8% of thetheory) of the above (2R)(+)-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acid aswhite cristals, which melt at 95°-96° ([α]_(D) ²⁰ =+37.5°±0.5°2% inacetone).

EXAMPLE 3 Preparation of (2R,S)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yl-oxy)-phenoxy]-propionicacid-ethoxycarbonyleth-1-yl ester ##STR19##

A solution of 10.6 g (0.030 mol) of (R)(+)-2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-phenoxy]-propionic acidchloride in 100 ml toluene is added slowly, while stirring into asolution of 4.9 ml (0.035 mol) of triethylamine and 2 ml (0.035 mol) of(S)-lactic acid ethyl ester in 40 ml of toluene, that is cooled in anice-bath. When everything is added, the ice-bath is removed and thereaction mixture is stirred for 3 hours at room temperature. Thereaction mixture is then poured into ice/water and the organic materialis extracted twice with ethyl acetate. The ethyl acetate layer is washedwith a saturated salt solution, dried over magnesium sulfate, filteredand evaporated. The residue is purified by chromatography over asilicagel column with a hexane/ethyl acetate solution. After evaporationof the solvent, there remains 8.9 g of the title product as a clear oiln_(D) ³⁵ 1.5223, [α]_(D) ²⁰ =+20.4±0.4 (acetone 0.02 g/l).

In analogy to Examples 2 and 3 the following 2R,S-enantiomers prepared:

    __________________________________________________________________________     ##STR20##                                                                    No.                                                                              R.sub.1                                                                          Q  R.sub.2                                                                          phys. data                                                        __________________________________________________________________________    2.01                                                                             CH.sub.3                                                                         O  CH.sub.3                                                             2.02                                                                             H  S  CH.sub.3                                                                         n.sub.D.sup.35 1.5623 [α].sub.D.sup.20 + 19.2 ± 0.5                  (acetone 0.02 g/l)                                                2.03                                                                             CH.sub.3                                                                         O  C.sub.2 H.sub.5                                                                  n.sub.D.sup.35 .5223 [α].sub.D.sup.20 + 20.4 ± 0.4                   (acetone 0.02 g/l)                                                __________________________________________________________________________

EXAMPLE 4 Production of a formulation with liquid active ingredients ofthe formula I (%=percent by weight)

    ______________________________________                                        Emulsion concentrates                                                                              (a)    (b)      (c)                                      ______________________________________                                        2-[4-(5-chloro-3-fluoropyridin-2-                                                                  20%    40%      50%                                      yloxy)-phenoxy]-propionic acid                                                (ethoxycarbonyleth-l-yl) ester                                                calcium dodecylbenzenesulfonate                                                                     5%     8%      5.8%                                     castor oil-polyethylene glycol                                                                      5%    --       --                                       ether (36 mols of ethylene oxide)                                             tributylphenol-polyethylene glycol                                                                 --     12%      4.2%                                     ether (30 mols of ethylene oxide)                                             cyclohexanone        --     15%      20%                                      xylene mixture       70%    25%      20%                                      ______________________________________                                    

Emulsions of any required concentration can be produced fromconcentrates of this type by dilution with water.

    ______________________________________                                        Solutions           (a)    (b)    (c)  (d)                                    ______________________________________                                        2-[4-chloro-3-fluoropyridin-2-                                                                    80%    10%    5%   95%                                    yloxy)-phenoxy-propionic acid                                                 methoxycarbonylthiomethyl ester                                               ethylene glycol-monomethyl ether                                                                  20%    --     --   --                                     polyethylene glycol MG 400                                                                        --     70%    --   --                                     N-methyl-2-pyrrolidone                                                                            --     20%    --   --                                     epoxidised coconut oil                                                                            --     --     1%    5%                                    ligroin (boiling limites 160-190° C.)                                                      --     --     94%  --                                     ______________________________________                                    

The solutions are suitable for application in the form of very finedrops.

    ______________________________________                                        Granulates              (a)      (b)                                          ______________________________________                                        (R) (+)-2-[2-[4-(5-chloro-3-fluoropyridin-2-                                                          5%       10%                                          yloxy)-phenoxy]-propionic acid (ethoxycar-                                    bonyleth-l-yl) ester                                                          kaolin                  94%      --                                           highly dispersed silicic acid                                                                         1%       --                                           attapulgite             --       90%                                          ______________________________________                                    

The active ingredient is dissolved in methylene chloride; the solutionis subsequently sprayed onto the carrier, and the solvent is evaporatedoff in vacuo.

    ______________________________________                                        Dusts                 (a)     (b)                                             ______________________________________                                        2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-                                                            2%      5%                                              phenoxy]-propionic acid ethoxycarbonyl-                                       methyl ester                                                                  highly dispersed silicic acid                                                                       1%      5%                                              talcum                97%     --                                              kaolin                --      90%                                             ______________________________________                                    

Ready-for-use dusts are obtained by the intimate mixing together of thecarriers with the active ingredient.

FORMULATION EXAMPLES FOR SOLID ACTIVE INGREDIENTS OF THE FORMULA I(%=PERCENT BY WEIGHT)

    ______________________________________                                        Wettable powders      (a)     (b)                                             ______________________________________                                        2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-                                                            20%     60%                                             phenoxy]-propionic acid methoxycarbonyl-                                      thiomethyl ester                                                              sodium lignin sulfonate                                                                             5%      5%                                              sodium lauryl sulfate 3%      --                                              sodium diisobutylnaphthalene sulfonate                                                              --      6%                                              octylphenolpolyethylene glycol ether                                                                --      2%                                              (7-8 mols of ethylene oxide)                                                  highly dispersed silicic acid                                                                       5%      27%                                             kaolin                67%     --                                              ______________________________________                                    

The active ingredient is well mixed with the additives and the mixtureis thoroughly ground in a suitable mill. Wettable powders which can bediluted with water to give suspensions of the required concentration areobtained.

    ______________________________________                                        Emulsion concentrate                                                          ______________________________________                                        (R) (+)-2-[4-[5-chloro-3-fluoropyridin-2-yl-                                                           10%                                                  oxy)-phenoxy]-propionic acid (methoxycar-                                     bonylthioeth-1-yl) ester                                                      octylphenol polyethylene glycol ether                                                                   3%                                                  (4-5 mols of ethylene oxide)                                                  calcium dodecylbenzenesulfonate                                                                         3%                                                  castor oil polyglycol ether                                                                             4%                                                  (36 mols of ethylene oxide)                                                   cyclohexanone            30%                                                  xylene mixture           50%                                                  ______________________________________                                    

Emulsions of the required concentration can be obtained from thisconcentrate by dilution with water.

    ______________________________________                                        Dusts                 (a)     (b)                                             ______________________________________                                        2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-                                                             5%      8%                                             phenoxy]-propionic acid (methoxycarbonyl-                                     eth-1-yl) ester                                                               talcum                95%     --                                              kaolin                --      92%                                             ______________________________________                                    

Dusts ready for use are obtained by mixing the active substance with thecarriers and grinding the mixture in a suitable mill.

    ______________________________________                                        Extruder granulate                                                            ______________________________________                                        2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-                                                              10%                                                   phenoxy]-propionic acid                                                       methoxycarbonyl-                                                              thiomethyl ester                                                              sodium lignin sulfonate  2%                                                   carboxymethylcellulose   1%                                                   kaolin                  87%                                                   ______________________________________                                    

The active ingredient is mixed and ground with the additives, and themixture is moistened with water. This mixture is extruded and then driedin a stream of air.

    ______________________________________                                        Coated granulate                                                              ______________________________________                                        2-[4-(5-chloro-3-fluoropyridin-2-yloxy)-                                                              3%                                                    phenoxy]-propionic acid (ethoxycarbonyl-                                      thioeth-l-yl) ester                                                           polyethylene glycol (MG 200)                                                                          3%                                                    kaolin                  94%                                                   ______________________________________                                    

The finely ground active ingredient is evenly applied, in a mixer, tothe kaolin moistened with polyethylene glycol. Dustfree coatedgranulates are obtained in this manner.

    ______________________________________                                        Suspension concentrate                                                        ______________________________________                                        (S) (-)-2-[4-(5-chloro-3-fluoropyridin-2-                                                             40%                                                   yloxy)-phenoxy]-propionic acid (ethoxy-                                       carbonyleth-l-yl) ester                                                       ethylene glycol         10%                                                   nonylphenolpolyethylene glycol ether                                                                   6%                                                   (15 mols of ethylene oxide)                                                   sodium lignin sulfonate 10%                                                   carboxymethylcellulose   1%                                                   37% aqueous formaldehyde solution                                                                     0.2%                                                  silicone oil in the form of a 75%                                                                     0.8%                                                  aqueous emulsion                                                              water                   32%                                                   ______________________________________                                    

The finely ground active ingredient is intimately mixed with theadditives. There is thus obtained a suspension concentrate from whichcan be produced, by dilution with water, suspensions of theconcentration required.

We claim:
 1. A compound of the formula ##STR21##
 2. A herbicidal andplant growth regulating composition comprising an effective amount of acompound according to claim 1 in combination with an inert carrier. 3.The method of selectively controlling grasses in cereals comprisingapplying to the grasses or their locus of growth an effective amount ofa compound according to claim
 1. 4. A compound of the formula ##STR22##5. A herbicidal and plant growth regulating composition comprising aneffective amount of a compound according to claim 4 in combination withan inert carrier.
 6. The method of selectively controlling grasses incereals comprising applying to the grasses or their locus of growth aneffective amount of a compound according to claim
 4. 7. TheR(+)-enantiomer of the compound according to claim
 4. 8. A herbicidaland plant growth regulating composition comprising an effective amountof a compound according to claim 7 in combination with an inert carrier.9. The method of selectively controlling grasses in cereals comprisingapplying to the grasses or their locus of growth an effective amount ofa compound according to claim 7.